I think the best way to look at the AxeFX-II is to look at other things in life. Let's use phones as an example. If you have a home phone, you basically press the buttons and call someone. You get an IPhone, you can do everything but scratch your own ass (and even that is probably an app now). They are both phones but one is way beyond the other.
Back to the AxeFX-II. You can buy one, plug in and run thru presets all night long, blown away at how awesome it sounds. If you never touched another setting or adjusted at all, it would still kick ass. However, if you say "I'd like to emulate running an old Marshall head into a 4x12 located approximately 2.5 feet from me, with a hint of hall reverb, the EL34 tubes running a tad hot, and an after market adjustment that my amp tech did with more saturation and brightness", then you might get overwhelmed.
People don't realize how awesome this amp is. It is like "Grand Theft Auto" in the amp world. Anything you want to do is just limited by your imagination. You can tweak things and pretend you are somewhere else. Some of us, really like that. If you like the idea of recreating Slash's sound to the point of nauseating realism, you can do that.
I look at it this way. I got my AxeFX-II about 3 years ago. When I first started, I was trying to tap into the different parts of the amp and had varied results. Over the past few years, I've learned so much about tone, amps, etc. and now can do so much more. Now that I understand the parts, I hear a sound in my head and know exactly what to adjust. I now know that "B+Constant" gives me immediate Metallica chug. I know "SAG" automatically gives me awesome modded Marshall tones. I could go on and on.
I think the AxeFX-II is the best investments I've ever made and I'm a bedroom player. I haven't gigged in years. I play guitar now every single night and haven't bought another amp since I got this thing. Guitars.....that's another story....